A fuel cell is a device for directly converting the chemical energy of a fuel into electrical energy.
A fuel cell comprises two gas diffusion electrodes, an anode and a cathode, and an electrolyte impregnated matrix. The matrix is disposed between the two electrodes. A catalyst layer is disposed on the electrolyte-facing surface of each electrode. In the operation of a typical fuel cell, a hydrogen-containing gas is fed to the back surface of the anode, and an oxygen-containing gas is fed to the back surface of the cathode. The gas is diffused through the electrodes and react at the catalyst sites to yield electrical energy, heat and moisture.
On the anode side of the cell, hydrogen is electrochemically oxidized to give up electrons. The electrical current so generated is conducted from the anode through an external circuit to the cathode. On the cathode side of the cell, the electrons are electrochemically combined with the oxidant. A flow of electrons through the electrolyte completes the circuit.
In large scale fuel cell power plants, the hydrogen rich fuel gas is typically provided by steam reforming a hydrocarbon fuel to produce the hydrogen fuel. A reformer combustor provides heat to the reformer. Anode exhaust from the fuel cell is typically used as fuel in the reformer burner.
Control of the flame temperature within the reformer burner is important as too low a flame temperature results in incomplete combustion of the fuel and a very high flame temperature may exceed the temperature resistance of the burner liner materials.